1. Field of the Invention
The present invention relates to a network interface apparatus provided for an image forming apparatus which is communicatably connected to an information processing apparatus for producing and transmitting print data and also relates to a control method, a program, and the image forming apparatus.
2. Description of the Related Art
Hitherto, a print system in which print data printed by the user is temporarily accumulated into a printing apparatus and a printing is requested to the print data accumulated in the printing apparatus has been proposed. As an example of such a print system, a system disclosed in Japanese Patent Application Laid-Open No. 2007-251279 is mentioned. According to such a literature, a mechanism in which a multifunction apparatus (or hybrid apparatus) is provided with an authenticating function and can print only the print data of the authenticated user in the print data which has temporarily been accumulated has been disclosed. Owing to such a mechanism, such a situation that printed matter is left for a long time can be prevented and the secure print system can be provided.
Hitherto, such a demand that the user wants to restrict a color printing has existed. As an example of a print system which satisfies such a demand, a system disclosed in Japanese Patent Application Laid-Open No. 2007-058746 is mentioned. According to such a literature, there have been disclosed: a first unit for inhibiting a color job by color information (additional information) added to a job; and a second unit for changing a color mode to a monochromatic mode and making an output restriction.
However, the print system as disclosed in Japanese Patent Application Laid-Open No. 2007-251279 can be applied only to an expensive printing apparatus such as a multifunction printer (MFP) called a hybrid apparatus in which a hard disk having a large memory capacity is equipped and which has a high processing ability. In many enterprises, local governments, schools, and the like, in order to reduce costs, many expensive printing apparatuses such as MFPs are not introduced but many reasonable printing apparatuses such as single function printers (SFPs) in which the hard disk having the large memory capacity is not equipped are introduced. Therefore, a print system which can be applied even to a printing apparatus such as an SFP and in which a printed matter is not left is demanded. For this purpose, it is considered to provide a print system in which a printing apparatus such as an SFP is provided with the authenticating function and is equipped with an externally-attached storing device (for example, USB memory) which can accumulate print data.
However, if the first unit proposed in Japanese Patent Application Laid-Open No. 2007-058746 is simply applied to the print system using the printing apparatus such as an SFP, such a problem that performance deteriorates extremely occurs. Japanese Patent Application Laid-Open No. 2007-058746 is made on the assumption that, as a prerequisite, whether or not the job is the color job can be discriminated with reference to the additional information formed by a printer driver. However, a printer driver which forms such a job that whether or not the job is the color job cannot be discriminated merely by referring to the additional information also exists. In such a case, in order to discriminate whether or not the job is the color job, a print server needs to analyze all PDL data formed by the printer driver. An analyzing time becomes long in proportion to a job size.
Particularly, in the case of the print system in which the external storing device is equipped for the printing apparatus such as an SFP, it is indispensable to cope with a countermeasure against a case where the external storing device has been stolen (removed). Therefore, when the print data is stored into the external storing device, it is necessary to encrypt the print data. In the case where the encrypted print data has been stored in the external storing device, even when a part (additional information) of the print data is merely changed in order to forcedly print the print data in the monochromatic mode, a process for decrypting (decoding) all of the print data and encrypting again is necessary, so that it further takes a time for the process. Such an increase in processing time due to the decryption and encryption causes the performance of the printing apparatus to be extremely deteriorated in the printing apparatus such as an SFP. This is because the printing apparatus such as an SFP has been designed for the purpose of only printing, applications which operate in the printing apparatus such as an SFP has been designed so that they operate on an NIC (network interface card) connected to the printing apparatus, and the processing ability is extremely inferior to that of the printing apparatus such as an MFP, the print server, or the like. If it takes a time for analysis such as a decryption (decoding) or the like, the system enters a state where the printing process has been stopped, and a large delay occurs in the business.
A problem also occurs in the case where the second unit proposed in Japanese Patent Application Laid-Open No. 2007-058746 is applied to the print system using the printing apparatus such as an SFP. That is, there is such a problem that a difference occurs between picture quality of a print image which is output by an ordinary monochromatic job and that by a job which has forcedly been converted into a monochromatic job. In order to forcedly monochromatically convert the job, it is necessary to rewrite the additional information of the job. In such a case, although the PDL (Page Description Language) data formed by the printer driver is color data, only the additional information is in a state where the monochromatic mode has been designated. After the job in which only the additional information has been designated in the monochromatic mode was input to the printing apparatus, it is monochromatically converted by the function of the printing apparatus main body and output. In the case of the ordinary monochromatic job, in other words, when the monochromatic job is formed by the printer driver, the PDL data itself is monochromatically formed. After the monochromatic job formed by the printer driver was input to the printing apparatus, the job is output as it is as a monochromatic job formed by the printer driver without executing the monochrome converting process in the printing apparatus main body. Since a main part (process) for forming the monochromatic job in the former job and that in the latter job differ as mentioned above, the difference occurs between picture quality of the print images which are output. That is, if the second unit proposed in Japanese Patent Application Laid-Open No. 2007-058746 is simply applied, when the user in which an output restriction of the color printing has been made inputs the color printing job, the job is always monochromatically converted and output, so that the desired picture quality cannot be obtained.
The reasons why the picture quality differs depending on the difference between the main parts (processes) are as follows. Since the SFP has initially been designed only for the monochromatic printing, besides the image processes for the monochromatic printing, image processes for the color printing are added. Although a halftone process, a multivalue/binary process, and the like are executed in the image processes, a halftone process according to the color data is executed in the image processes for the color printing, and a halftone process according to the monochromatic data is executed in the image processes for the monochromatic printing. Therefore, a difference occurs between the picture quality of the print image which is output in the case where the halftone process is executed to the color data and the data is converted into the monochromatic data (in the case where the color data is forcedly monochromatically converted) by the image processes for the color printing and that in the case where the halftone process is executed to the monochromatic data by the image processes for the monochromatic printing.